Thermostatically-controlled choker for carburetors



Aug. 7; 1928. 1,679,999

c. E. WILLIAMS THERMOSTATICALLY CONTROLLED CHOKER FOR CARBURETORS Filed June 21. 1923' /5 /9 avwaw co'c Patented Aug. 7, 1928.

I [TED STAT-ES 1,519,999 PATENT OFFICE.

CHARLES ERNEST WILLIAMS, 0]? DETROIT, MICHIGAN, ASSIGNOR TO GENERAL MOTOR/d CORPORATION, OF DETROIT, MICHIGAN, A. CORPORATION OF DELAWARE.

THERMOSTATICALLY-CONTROLLED CHOKER FOR CABBURETOIW.

Application filed June .tl, 19%. Serial No. M6,80l.-

My invention relates to carbureting devices for use with internal combustion engines to supply a combustible mixture of air and liquid fuel for use therein; and particularly to controlling means associated with the carburetor and acting to facilitate the starting of the engine by insuring the supply of a proper combustible mixture thereto initially and throughout the warming up period; during which most carburetors are inefficient and do not produce a properly proportioned mixture.

Carbureting devices for the purpose stated are commonly provided with regulating means operable by the driver of the motor vehicle which the engine is assumed to drive for increasing the amount of liquid fuel in the mixture supplied to the engine at starting, to thereby provide a mixture which may 2ft b c more readily ignited and burned in the engine cylinders; which are obviously comparatively cold when the engine is at rest, especially if it has been out of operation for any considerable time. Such operation, however, is wasteful of liquid fuel; and 1t 15 expected that the operator will reduce the amount of fuel'in the mixture to a minimum after the engine is in operation and has become heated, although he not infrequently fails to do so because of the attention necessary to be given to the vehicle after the engine is in operation or fails to do so promptly, with a consequent waste of fuel each time the engine is started.

The principal object of my invention therefore is to provide automatic control mechanism for a carburetor which, without attention on thepart of the operator, will operate upon the carburetor to secure an en riched mixture at starting and when the engine is cold or comparatively so; and which will also and likewise without attention on the part of the operator act to restore the carburetor to its normal condition after the engine has been started and has become heated; the carburetor then supplying, as will be appreciated, a much leaner mixture, that is, one in which the quantity of liquid fuel therein is materially reduced from the quantity necessary to secure proper starting and efficient operation during the usual warming up period of the engine; the control of the carburetor in the manner aforesaid being accomplished by the use of a suitable thermostat operating thereupon, which thermostat ,is heated preferably by the exhaust gases'escaping from the engine, although also capable of being heated by the cooling liquid whereby the engine is cooled.

A further object of my invention is to provide various improvements in and relating to the arrangement of the thermostat relative to the carburetor of the engine and to the heater ordinarily employed therewith to heat the combustible mixture produced by the carburetor, whereby a better and more efi'ective control of the mixture is secured than has heretofore commonly been the case in thermostatically controlled carburetors.

With the above and other objects of invention in view my invention consists in the improved thermostatically controlled carburetor illustrated in the accompanying drawing and hereinafter described and explained; and in such variations and modifications thereof, within the scope of the concluding claims, as will be obvious to those skilled in the art to which my invention relates.

In the drawing accompanying and form ing a part of this specification, and wherein the preferred embodiment of my invention is illustrated:

Figure l is a view showing a type of carburetor and heater for the mixture produced thereby in use at the present time, the same being: equipped with thermostatically con trolled mechanism for regulating the auxiliary air valve; said .view being partly in section and partly in elevation.

Figure 2 is a view showing the same carburetor partly in elevation and partly in section upon a vertical plane at right angles to the plane of Figure 1.

Flgure 3 is a fragmentary view showing a detail of the controlling mechanism.

Figure 4 is a fragmentary sectional view showing a different form of thermostat than the form shown in Figures 1 and 2, as well also as a difi'erent method of heating the same.

Figure 5 is a view showing still another form of thermostat for controlling the auxiliary air supply valve of the carburetor.

Figure 6 isa view also in section showing a still further form of a thermostat.

' Figure 7 is a fragmentary sectional view ltlll which it has been adjusted.

FigureS is an end view of the design shown in Figure 7.

Referring now to the drawing, and first to Figures 1 and 2 thereof, my invention is illustrated as used in connection with a com- 7 bfned intake manifold and heating device therefor designed for use in connection with for are located between two diverging cylinder blocks. The carburetor as a whole is designated by the numeral 10 and the combustible mixture produced thereby flows through a passage 11 which divides into two branches 12, 13 extending downward, and the extremities of which are connected with the intake manifolds of the two cylinder blocks. The upper portions of the outlet passage 11 and of the branches 12, 13 are surrounded by a heating chamber 14 into which exhaust gases flow from the exhaust .manifolds of the two cylinder blocks through conduits 15, 15 in the same general manner as disclosed in the patent to Litle, No. 1,448,072. The upper wall 16 of the heating chamber in this particular form of my invention is made flat, and is continuous and imperforate throughout a considerable area, as will be understood from Figures 1 and 2 of the drawing.

Fastened to the flat top wall of the exhaust heated intake conduit above described is a cover 17 which is open along its under side, and is secured to the top wall of the heater in any appropriate way; from which it follows that the cover and the top wall provide a chamber 18 within which the thermostatic element involved in my invention is located.

The thermostatic member above referred to is of the bi-metallic type and is designated by the reference numeral 19; and the same is shown as a floating memben, one end thereof being fastened to the top wall by therm screws 20, and the free end thereof being therefore free to move up and down within the chamber 7 as the temperature therem varies. The more expansible member of this t, brass being the metal ordinarily employ is arranged upon the under side so that when the temperature within the chamber is comparatively low the thermostat will occupy substantially the position in which it is shown in Figure-1, while as the temperature rises within the chamber the free end of the thermostat will move upretor, the intake manifold and a heater thereward'into substantially the position shown in dotted lines in said figure.

Supported in bearings in the side walls of the cover 17 is the shaft 21, having an arm 221 inside the chamber and arranged so that the free end of the thermostat may engage the same. Secured to one outer end of this shaft is an arm 22; and 23 designates.

a link the upper end of which is connected with the free end of said arm and the lower end of which is connected with a rocking stop member 24 loose upon a shaft 25 supported in bearings provided in the wall or casing of the ,carburetor 10. This shaft 25 has an arm 26 disposed inside a chamber 27 of the carburetor, and acts through a spring 28 upon a valve 291 which controls the supply of auxiliary or diluting air to the interior of the carburetor casing. These carburetor featuresyhowever, form no part of the invention to which this present applicatlon relates.

The rocking stop lever 24 is provided with a stop 29 adapted to engage a lug 30 which is fast upon the shaft 25; from which it follows that motion in a counterclockwise direction imparted to the member 24 will cause the stop 29 thereof to engage the lug 30 and rotate the shaft 25 and arm 26 in a corresponding direction; with the result that the spring 28 will be compressed, thus increasing the resistance opposed to opening movement of the auxiliary air valve 291, which opens by suction, as will be appreciated.

In view of the premises it will be appreciated that when the temperature within the chamber 18 is low and the thermostat 19 is in its down position shown in full l'nes the free end thereof will press downward upon the arm 221, thus holding the link 23 in an up position, with the stop 29 engaging the lug 30. In this position of the parts the spring 28 is placed under considerable compress'on, with the result that the auxiliary air valve 291 is held closed or nearly so, or is restrained from o ning by a greater force than would otherwise act upon said valve. It will be appreciated that under these conditions with opening movement of the valve opposed by the spring 28 the mixture supplied to the engine will be a mixture more than ordinarily rich in liquid fuel, as it is then the rich mixture produced by the-atomizing nozzle of the carburetor undiluted by air flowing into the carburetor casing past the auxiliary air valve. In this connection, however, I wish to state that the spring 28 need not be sufliciently stiff to hold the valve 291 in actual contact with its seat; as the result to be attained, that is the production of an abnormally rich mixture at starting, will be attained if the valve is subjected to a spring pressure of such magnitude as to lll till

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ation. 1

The richmixture produced as above pointed out facilitates the starting oi? the engine, as such a mixture is more readily ignited than the leaner mixture supplied when the engine is in operation. As exhaust gases from the initial explosions flow through the conduits 15, 15, the temperature within the chamber 18 rises with the result that the free end ol the thermostat soon moves away from the arm 221, thus permitting the link 23 to move downward and the stop 29. to move out of stopping engagement. with the lug 30. This permits the arm 26 inside the carburetor chamber to move under the influence of a returning spring in a clockwise direction, thus relieving the spring 28 from the compressing action of the free end of said arm. Tn the returned and normal position of the arm 26 an arm 300 upon the shaft 25 engages the end oil a set screw 301, in which position'it will be appreciated that the action of the spring 28 in holding the valve 291 upon its seat is reducedto its lowest permissible magnitude.

ln constructing and assembling the parts and in adapting them to one another the thermostat 19 is ordinarily so designed and arranged that its free end may have considerable movement without engaging the end oil the arm 221, from which it follows that the thermostat actsto restrain opening movement of the valve 291 only when the engine and the elements herein described are in a comparatively cool condition; and that the tree end out the thermostat moves away from the.

free end ot the arm 221 upon a comparatively slight rise in temperature within the chamber 18. The thermostat may therefore assume a large number of positions, due to variations in temperature within the cha ber 18, in all of which it will be free from the arm 221 and. will therefore exert no holding down action upon the valve 291. This provides a thermostatic control device in which slight variations in temperature will not bring the auxiliary air valve controlling mechanism into active operation, and said mechanism coming into operation acting in the manner above pointed out only upon such a fall of temperature as occurs after the engine has been at rest fbr some time, and at starting when the temperature of the engine and mir rture supply mechanism is at its lowest temperature, or at least at an abnormally low temperature.

Tn the term of my invention shown in Figure 4, the reference numeral 31 designates a casing surrounding the conduit.

through which combustible mixture flows from the carburetor to the engine to thereby provide a heating chamber 32 within said casing. In this form of my invention the heating chamber is open along its up er side; and said opening is closed by a hol ow cover 33 within which the thermostat ele-' contact with the thermostat. Tn this form of my invention the thermostat 34: is of the coiled ribbon type; one end thereof being anchored at 35 to a hollow bearing cap 36 which is supported in an opening in the end wall of the cover 33, and is angularly adjustable in said opening; while the other end of the thermostat is operatively connected at 37 with a shaft 38 having hearings in the bearing member 36 and in another bearing member located in the opposite wall of the cover 33. .The shaft 38 carries an arm 39 which is operatively connected with the upper end of a link 40 corresponding in all essential particulars with the link 23 hereinbetore mentioned. Tn this form of my invention the arrangement of the parts is such that when the thermostat is cool the auxiliary air inlet valve of the carburetor will be yieldingly held against its seatwith more force than is the case when the engine has become heated up and the carburetor is operating normally, to thereby secure enriched mixture at starting. its the engine warms up the force with which the auxiliary air inlet valve is held against its seat gradually decreases, and finally ceases to act, there by leaving the valve to perilorm its proper function alter the necessity for an enriched starting mixture ceases.

Figure 5 shows a form of my invention in which the thermostat 4:1 is housed within a closed chamber provided by a cup-shaped receptacle 42, which is inserted through an opening in one of the side walls 43 ot a chamber 4e1- through which a heating medium flows whereby somewhat more effective heating of the thermostat is secured than in the term of my invention illustrated in Figures 1 and 2; while at the sametime and as in said first described form the thermostat is located in a separate chamber and is protected from the direct action of the exhaust ases or equivalent heating medium. in this horm of my'invention the bi-metal thermostat a1 is in the i'orm of a spiial spring, the

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more enpansible metal being outside so that the coil tends to unwind as it cools; one

end of the thermostat being fastened to a upon the auxiliary air valve of the carburetor in substantially the same way as hereinbefore explained.

Figure 6 shows a form of my invention corresponding in a sense with the form shown in Figure 5 in that the thermostat is contained within a housing 48 extending into the heating chamber 49 so as to secure efiective heating of the thermostat. In this form of my invention, however, the thermostat is made up of a corrugated metal tube 50, one end of which is anchored at 51 and the other end of which is operatively connected with a reciprocating rod 52, the outer end of which is in turn connected with a link 53 through a bell crank lever 54:. In this form of my invention the space within the housing 48 and outside the corrugated tube 50is preferably partly filled with a liquid such, for example, as alcohol, which vaporizes at a comparatively lowtemperature and exerts a pressure tending to collapse the thermostat and move therod 52 to the left of said figure.

Figures 7 and 8 show a modification of the form of my invention illustrated in Figure 4, whereby the automatic choking action produced by the thermostat can be manually discontinued by the operator, and the auxiliary air valve restored to its normal operative condition at any time, regardless of the temperature to which the thermostat is subjected or the position which it then occupies.

The manner in which this result is obtained will be understood by reference to Figures 7 and 8, in which the helically coiled ribbon which constitutes the thermostat 64 within the heating chamber 76 is mounted on and i securelysfastened at 65 to the shaft 66, one end of which is'rotatably supported in the threaded bushing 67 wh ch closes the 0 en; ing in the end wall of the housing 68. I he opposite end ofthe thermostat 64 is mounted on and securely fastened at 69 to a sleeve 7 0 which is rotatably supported in a threaded bushing 71, said sleeve acting in addition as a bearing for the inner end of the shaft 66. An arm 72 is firmly attached to the shaft 66, and is held in either'an in or;an out position by means of a rod or equivalent member connected with said arm and extending to a position accessible to the operator of the vehicle, and terminating in air valve of the carburetor, as in the forms of my invention hereinbefore described.

The thermostat 64 being arranged with its more expansible,(brass) member inside will slightly unwind when heated, thus moving the sleeve and arm 74 in a clockwise direction relative to the shaft 66, thereby lowering the link and releasing the spring pressure upon the auxiliary air valve, as hereinbefore explained; further movement of the thermostat due to increasing temperature operating merely to rotate the arm 7 4 farther away from the lever 73 without further effect or damage to the thermostat, which might occur if movement of the arm in question was prevented at high temperature.

Inasmuch as the action of the thermostat should be entirely automatic under all conditions, except under the abnormal conditions above referred to, when its. operation is temporarily arrested, it will be appreciated that the operator by shifting the position of the lever 72 into its out position indicated, will rotate the shaft 66, the thermostat 64, the sleeve 70, and the stop arm 74 into a position such that the normal operation of the carburetor will be restored, and insure complete release of the lever 73 and link 75 to such an extent that the full range of thermostat movement at the lowest temperature likely to be encountered will not cause the arm 74 to come into operative contact with-the lever 73, while movement of lever 72 in an opposite direction permits the thermostat .to operate automatically as herein before explained, during the remainder of the warming up period; this movement being so limited as to insure complete automatic release of the auxiliary air valve due to the unwinding action of the thermostat when the engine has been warmed up to such a degree as to operate satisfactorily without enrichment of the combustible mixture.

While I have hereinbefore referred most usually to exhaust gases from the engine as employed for heating the thermostat, I may, if for any reason such a scheme is preferable, use the liquid whereby the engine is cooled for heating the chamber with which the thermostat is associated; or the thermostat itself may be heated b direct contact therewith of the cooling liquid of the cooling system of the engine.

In all forms of my invention it will be appreciated that I provide an automatic thermostat device which, without attention on the part of the operator, will so cooperate with the carburetor as to produce an enriched mixture when the engine is to be started. At the same time and in all forms, and also without attention on the part of the operator,-the thermostat will act automaticallyrin such a manner as to restore the carburetor to its normal operative condition lid ill

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emme as the engine becomes warmed up, thus securing a normal operation of the carburetor after the engine is in operation and as soon as the parts become heated to such a temperature as to insure continued operation of the engine by a properly proportioned mixture furnished by the carbureting device.

Having thus described and explained my invention it claim and desire 'to secure by Letters Patent:

1. In combination with an internal combustion engine, and a carburetor thereof having an air inlet passage leading thereinto; a valve for controlling the how of air through said passage; means acting upon said valve for restraining the opening thereof when the engine is being started; a thermostat and means for heating the same; and means controlled by said thermostat for in: terrupting the action of said restraining means after the engine has been started.

2. ln combination with an internal combustion engine, and a carburetor having an air inlet passage leadin thereinto; a thermostat and means where y the same is heated by heat derived from the engine; and means controlled by said thermostat for restraining the fiow of air through said passage when the engine is being started and for interrupting such restraining action after the engine has been started.

3. In combination with an internal combustion engine, and a carburetor having an air inlet passage leading thereinto; a valve for controlling the flow of air through said passage; a heater adapted to heat the combustible mixture produced by said carburetor; a thermostat associated with said heater so as to be heated thereby; and means whereby and through which said thermostat acts upon said valve to restrain the flow of air through the passage aforesaid when the engine is being started, and to interrupt such restraining action when the engine has been started.

4. In combination with an internal combustion engine, and a carburetor having an air inlet passage leading thereinto; a valve for controlling the flow of air through said passage; a heater associated with said carburetor and adapted to heat the combustible mixture produced thereby; a cover associated with said heater, and having an internal chamber; a thermostat located within said chamber and adapted to be heated by heat derived from said heater; and means intermediate said thermostat and said valve whereby the latter is operated to restrain the flow of air through the passage aforesaid when the engine is being started, and is freed from such restraining action after the engine has been started.

5. In combination with an internal combustion engine. and a carburetor having an air inlet passage leading thereinto; a valve for controlling the flow of air through said passage; a heater associated with said carburetor and adapted to heat the combustible mixture produced thereby; a cover associated with said heater and having an internal. chamber; a thermostat located Within said chamber and adapted to be heated by heatderived from said heater; and means whereby and through which said thermostat acts upon said valve to restrain the flow of air through the passage aforesaid when the engine is being started, said thermostat being in operative engagement with said restraining means when the engine is being started, and out of engagement with said means after the engine has become heated.

6. In combination with an internal combustion engine, and a carburetor having an air inlet passage leading thereinto; a valve for controlling the flow of air through said passage; a heater adapted to heat the combustible mixture produced by said carburetor, and which heater is provided with a top wall; a thermostat one end of which is secured to said top wall; a cover secured to said top Wall and enclosing said thermostat; a shaft supported in bearings provided in said cover and having an arm which is engaged by the free end of said thermostat when the engine is being started; and means intermediate said shaft and said valve through which the latter is controlled by said thermostat; the location and arrangement of said thermostat being such that the free end thereof is out of engagement with said arm after the engine has been started.

In testimony whereof I affix my signature.

CHARLES ERNEST WILLIAMS. 

